89 MJ

Unfortunately, I’m not sure. I do know the high altitude CPS has 5* more timing than a regular.

Do you have a regular CPS or a high altitude CPS? Immediately after the engine swap in my truck, it started doing this and did so for probably 1500 miles or so. At that point, I switched to the high altitude CPS and have had it happen much less, it maybe happens a few times in the first hundred or two hundred miles of pulling the truck out of winter storage, then it gets itself sorted out. My other thought would be that it runs too rich with the current injectors. Do you have a REM? I'd be curious to see what it says for O2 information on deceleration.

I also picked up some shocks from one of the Vail off road guys.

Did another wheeling trip with the Vail off road group to Sonoita, AZ from Vail, AZ. Got a few more scratches on the sliders, but the Jeep did great. Also saw a neat MJ and CJ.

Click on your username in the top right, then "profile", then "see my activity" on the right side of the ribbon showing posts and days won, and then "Topics" under Forums on the left side

Definitely keep that external slave, it is definitely an upgrade. The new internal slaves seem to lack in quality.

That would be a perfect engine! As long as it isn't too difficult compared to an LS, that would definitely be the way to go. This would be neat too, especially if it isn't a daily driver. It's always been my (admittedly biased) understanding that GM swaps are typically a lot cheaper and have better parts availability, which is why I'm assuming you added the time and money to burn part.

Would you keep the Vortec FI on the SBC? Personally, I prefer an SBC to an LS because it has always felt to me that an SBC's torque peak is at a lower RPM than an LS's. That said, a Chevy 350 is old technology at this point, I don't think they've been put in a new GM vehicle since 2002, nor is it as efficient as an LS. I would guess that the work involved for a small block versus an LS would be about the same. The LS would more than likely cost more than the SBC, but I think the higher resale value more than makes up for that difference. I think an LS is the way to go on this one.

Agreed. For daily driving, it is plenty capable of doing what I need on a day to day basis. When it comes time to actually hook a trailer up, I will not use my MJ.

When you look at what an MJ can haul compared to most new half tons, there is no comparison, the MJ is far more useful as a truck

I really like that the Renix header panel is going back on with a 10 slot grille. Doesn't getter better than a 10 slot, IMHO

I really, really like my Comanche. It is a fun truck and is pretty capable for its size. The bed is great for hauling smaller things, but I hate towing or hauling heavy with my MJ. It just does not feel very planted, but some of that is the fact its a short bed and the way I've built the truck.

September 2026 - The @OSCDumpTruck Build Thread- The OSC Dump Truck (89 Sport Truck 2.5L) Year/Model - 1989 SporTruck rust free edition Drivetrain- 2.5TBI/AX5/231 with Dana 30/35 Cooling- Stock radiator with bypassed heater valve Electrical/Ignition- DIY 4 gauge Big 7 Battery cables, Headlight harness upgrade, group 34 battery Suspension/Steering- Stock suspension height, all new bushings all around. KYB gas adjust shocks, energy suspension sway bar bushings. Power steering Interior- Grey/black two tone interior consisting of factory black interior pieces. SMS black headliner, black reupholstered bench seat, dashcoversusa dashdura cover (highly recommended if your dash is cracked) Cassette radio Brakes- stock and all replaced, custom rear load sensing valve arm Lighting- Dash bulbs stock, added interior foot bulb brackets with leds, cab corner housings replaced with Euramtec. Rampage headlight housings Exterior- 97-01 header panel swap (soon to be going back to Renix header panel with 10 slot grill) and JCR diy front bumper (soon to be powder coated stock front bumper) and original refinished rear bumper with krustyballer hitch receiver Wheel & Tires- mammoth boulder 15x8 wheels with KO2 235/75/15 tires Misc- Vintage Sony CPA-7 cassette adapter for music Best MJ story- A few years ago I had it parked in front of my house. Later that day I noticed with driver side cab corner had been bumped into by a car, hit and run. I ended up trying to get a claim and got it fixed at a restoration shop. The person who did the bodywork did a horrible job, so I ended up taking it to another shop and he was able to do better. But for a while I drove it around with a grey square of primer that eventually cracked from sun exposure. First body shop claimed the repair was acceptable but it absolutely was not. The second body repair was painted with black spray paint. Hoping to finally be rid of that spot (although barely noticeable) once we hopefully get it repainted factory black. CC is Awesome! Why? Comanche Club is awesome for all of the information and experience it has to offer. Out of all the forums, I have such an easy time figuring things out and seeing other people’s builds.

People would definitely be interested in that truck, especially being low mileage

I just did this to my Wrangler (though not the hothead ones because I didn't want to spend that much money on something I wasn't convinced would work). It makes a huge difference and was well worth the money.

Ok, as long as the rust was slowed way down or stopped with that rust seal, you’ll be good for a while. It’s not “the right way”, but it’s definitely better than before and will hold it until you decide to replace the pans, if ever.

Please tell me you cut out the rust, welded new metal in, then did the bodywork over the welds and didn’t just put filler straight over rust holes because that’s a temporary repair that’s just going to speed the rust up. From the inside or the outside? If you did this from the inside, the flex seal is going to hold moisture up against the metal and cause worse rust issues.

This. Especially the width is why I’d steer away from an 8.8. The Explorer Sport Trac is almost the same width as an MJ rear though. I would either stick with the D44 or order a brand new 9”.

BoxyJeep has videos on their YouTube channel. That’ll explain it way better than I can.

Or just do an electric speedo conversion by @boxyjeep https://boxyjeep.com/products/87-90-electric-speedometer-conversion-full-kit

Went out with the Vail Off-road group a couple of weeks ago. Found an obstacle I wasn’t able to do, but I suspect it could make it with a line adjustment.

Any updates?

I would check for vacuum leaks around the intake manifold, especially where the manifold bolts to the head.

I think we'd probably need current pics and more details on what the truck is like currently in terms of engine, trans, mileage, etc.

I'm surprised this hasn't sold yet. Looks like a straight and solid body. Figure also what a 4L80 is worth too. Then these later small blocks were often times a roller cam block. They didn't all have the roller cam, but I think they all were machined for a roller camshaft.